David Ramos via Getty Images
People look toward the scene of the attack

Two people have been arrested but police said neither of them was the van’s driver.

Hours after the attack, the scale of what happened remained unclear.

Police said an explosion at a house in the Catalonian village of Alcanar, which killed one person on Wednesday night, was related to the Barcelona attack.

However, a driver, who drove into two police officers later on Thursday and was then shot dead, was not related to the terror attack, police said.

Theresa May, Boris Johnson and Sadiq Khan - whose city has suffered two terror attacks this year - were among the politicians condemning the attack and expressing solidarity with Spain.

May said: “I am sickened by the senseless loss of life in Barcelona... Following the attacks in Manchester and London, Spain stood alongside the British people. Tonight, Britain stands with Spain against the evil of terrorism.”

My thoughts are with the victims of this barbaric terrorist attack in the great city of Barcelona and with their brave emergency services.